This paper shows an experimental study on rheological behavior of hybrid nanofluids made of Al2O3-TiO2 suspended in pure water. Also, simple nanofluid samples, with various volume fractions of Al2O3 and TiO2 were prepared and used for comparison. Viscosity measurements were achieved at room temperature and the shear rate between 10 and 1000 1/s for all samples. Experimental outcomes shown that all samples showed non Newtonian behavior and followed the Ostwald model. Furthermore, the power law index and consistency index were discussed in detail. The curve-fitting technique was applied and results helped us tailoring few correlations in order to describe the rheological behavior. A regression analysis was also done in order to connect the relative viscosity with volume fractions of both nanofluids and hybrid nanofluid.